@Xyph - is the Bonus mana counter on Archangel's tied to the item (or tear component)? There are items which grant bonus mana (i.e. manamune). If it's not tied to the item specifically for the 750 count=upgrade to Seraph's Embrace, things like innate bonus mana gain per level, Ryze's Desperate Power, or even Clarity would enable builds that would exponentially speed up the rate that the Staff goes to Embrace.

Bonus Mana is tied to the 'Mana Charge' passive itself - which is tied to only the item itself. There's no getting around charging the item if you want it to upgrade.

Isn't there a good reason Blitz's passive doesn't actually steal mana? Aren't you concerned that because the item may effectively silence your character (and since you never actually upgrade it, there's no choice not to), it will be a worse item?